Does Runway backup need a reset after change of backup method?

I've been backing up a Runway site to DropBox for a month or so. The daily backup plan was working fine and all the assets gradually got backed up too. I've now switched the backup to use Amazon S3. The daily backup (.gz file) is now appearing in the S3 bucket, but the assets are not backing up. Nothing new has probably been added in the last few days anyway, but I expected all the assets to gradually appear on S3 over a few days, instead of going to DropBox.

Is there some sort of 'reset' I'll need to do to encourage Runway back to backup all the assets to the new location at S3, regardless of the fact its already backed them up to Dropbox?